TY - JOUR
T1 - On the mechanism for formation of RNA · DNA complexes from lymphocytes
AU - Mendelsohn, J.
AU - Castagnola, J. M.
AU - Goulian, M.
N1 - Funding Information:
Supported by NIH research grants CA 11971 and CA 11705 from the National Cancer Institute, Cancer Research Funds of the University of California and American Cancer Society Grant NP-122. Dr Mendelsohn is the recipient of NIH Research Career Development Award CA 70891 from the National Cancer Institute.
PY - 1975/10/15
Y1 - 1975/10/15
N2 - Early intermediates in DNA synthesis by human lymphocytes were studied for the possible association of RNA with nascent DNA. Nucleic acid extracts from cells pulse-labeled with [3H]uridine contain RNA that is associated with DNA in Cs2SO4 equilibrium density gradients. The amount of RNA bound to DNA was greatly reduced by repeated denaturation and equilibrium centrifugation. An apparently similar complex between RNA and DNA was formed in reconstruction experiments in which purified [3H]uridine-labeled RNA was mixed with purified DNA. The association between RNA and DNA could be eliminated in the reconstruction experiments and greatly reduced in extracts from pulse-labeled cells by denaturation and equilibrium centrifugation in the presence of formaldehyde. These studies demonstrate that noncovalent bonding between RNA and DNA can account for most, and possibly all, of the RNA with density close to DNA in Cs2SO4 gradients of nascent DNA preparations. In addition, the results indicate that ribonucleotide, demonstrated by other methods to be covalently bound to nascent DNA, must constitute less than 1 5 of the total nucleotide in the molecule.
AB - Early intermediates in DNA synthesis by human lymphocytes were studied for the possible association of RNA with nascent DNA. Nucleic acid extracts from cells pulse-labeled with [3H]uridine contain RNA that is associated with DNA in Cs2SO4 equilibrium density gradients. The amount of RNA bound to DNA was greatly reduced by repeated denaturation and equilibrium centrifugation. An apparently similar complex between RNA and DNA was formed in reconstruction experiments in which purified [3H]uridine-labeled RNA was mixed with purified DNA. The association between RNA and DNA could be eliminated in the reconstruction experiments and greatly reduced in extracts from pulse-labeled cells by denaturation and equilibrium centrifugation in the presence of formaldehyde. These studies demonstrate that noncovalent bonding between RNA and DNA can account for most, and possibly all, of the RNA with density close to DNA in Cs2SO4 gradients of nascent DNA preparations. In addition, the results indicate that ribonucleotide, demonstrated by other methods to be covalently bound to nascent DNA, must constitute less than 1 5 of the total nucleotide in the molecule.
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U2 - 10.1016/0005-2787(75)90095-7
DO - 10.1016/0005-2787(75)90095-7
M3 - Article
C2 - 1186171
AN - SCOPUS:0016701429
SN - 0005-2787
VL - 407
SP - 283
EP - 291
JO - BBA Section Nucleic Acids And Protein Synthesis
JF - BBA Section Nucleic Acids And Protein Synthesis
IS - 3
ER -